Place green and red bell peppers, jalapeños, celery, carrot, onion, and cauliflower in a bowl. Stir in salt and add enough cold water to cover. Cover and refrigerate overnight.
The next day, drain the salty water and rinse the vegetables.
Mix garlic, oregano, red pepper flakes, black pepper, and olives. Add vinegar and olive oil and mix well.
Combine dressing with the vegetable mixture, cover, and refrigerate for 2 days before using.
Notes
This source describes a refrigerated giardiniera, not a shelf-stable heat-processed canning recipe. Keep refrigerated.